Over the last year the EM lab has collaborated with 10 different CBER laboratories in studies related to product safety, virus-cell interactions and vaccine development. Examples of each are listed below. (1) Product Safety a) description of an endogenous porcine retrovirus capable of infecting human cells (with C. Wilson, DCGT) b) expression of prion protein on platelets (with J. Vostal & T. Mondoro, DH) c) examination of cell culture supernatants for the presence of adventitious agents (with P. Krause, DVP) (2) Virus-Cell Interactions a) research on rubella virus and dengue-2 virus-induced apoptosis (with R. Duncan, DAPP and R. Levis, DVP) b) research on the control of retroviral replication in mouse melanoma cells (with E. Gorelik, Pittsburgh Cancer Institute & V. Hearing, NCI (3) Vaccine Development a) investigation of particle formation following the introduction of viral sequences into cultured cells (with A. Khan & T. Galvin, DVP; I. Berkower, DAPP) b) research on dengue-2, rubella, and sindbis virus replication in cell lines expressing dengue -2 NS1 protein (with R. Levis, DVP) The EM lab has also entered into an Interagency Agreement with the Cell Biology lab of NCI for the study of melanocyte-keratinocyte interactions (with V. Hearing & V. Virador)